1. Field of the Invention
This invention relates to magneto-optical current sensors that utilize the Faraday rotation effect and, more particularly to such sensors that employ thermal-mechanical means for rotating the sensor in response to changes in ambient temperature.
2. Description of the Prior Art
Developmental efforts of the device of this invention are based upon the principles of the Faraday effect which was first discovered in 1845. Briefly, when a plane of polarized beam of light passes through certain transparent substances along the lines of a strong magnetic field, the plane of polarization of the emergent light is different from that of the incident light. Under the influence of a magnetic field H the plane of polarization undergoes a rotation d.theta. proportional to H', which is the component of H that is parallel to dl, and depends upon the Verdet constant (V) of the magneto-optical material utilized. This can be expressed as d.theta. equals VH'dl, wherein "dl" is the length of the path.
Associated with the foregoing is the fact that the Verdet coefficient is dependent upon temperature which reason variations in temperature must be compensated for in order to obtain accurate current information with a current sensor. Although various means have been devised for compensating for temperature variations a simple means to offset the temperature dependence of the material employed in a current sensor is desirable where a moderate degree of accuracy is required.